There is no difference between more shares of a relatively cheaper stock and less shares of a relatively more expensive stock. When you invest in a stock, the percentage increase (or decrease) in the share price results in gains (or losses).
This is a fundamental concept of investing. Your question suggests that you would benefit from further research before investing your money. Trading real dollars can be difficult without a strong understanding of the principles involved. Investing your money without a good knowledge base will likely be stressful and could have a discouraging effect if it doesn't go well.
Before you open an investment account, read up on investing fundamentals, particularly mutual funds as those can be a great place to start as a new investor. There are many sources of information including books, websites such as http://investor.gov/investing-basics and this website. Don't skip the sections on taxes, as those matter just as much and sometimes more than the simple buying and selling. You might look at tax advantaged accounts, such as 401k's, IRA's, etc. It shouldn't take long but it will be one of the most important things you do as a beginning investor. Everyone has to start here. Understanding the vocabulary and concepts will likely save you time and money throughout your investing life.